A disk drive system typically has one or more magnetic recording disks and control mechanisms for storing data within the disks. The magnetic recording disk is composed of a substrate and one or more layers deposited above the substrate. Typically, to provide a reliable head-disk interface, a carbon-based overcoat (COC) is applied above a base structure of the magnetic recording disk and a lubricant layer is disposed above the COC so that the head then flies over the lubricant layer.
An example of such a lubricant is a Fomblin-based perfluoropolyether compound (e.g., “Z-Dol,” commercially available from Solvay-Solexis of Thorofare, N.J.). Fomblin-based compounds are known to react with metals, such as alumina, contained in head members, cleaving the main chain of the perfluoropolyether and depolymerizing the lubricant into volatile byproducts. Phosphazene additives inhibit degradation of disk lubricant that occurs during head-disk contact and, thereby, improve the head-disk interface durability. For example, a phosphazene functionalized perfluoropolyether material, such as “Phospharol A20H,” commercially available from Matsumura Oil Research Corp. (MORESCO) of Japan, may be combined with Fomblin Z-Dol.
To further increase storage densities and processing speeds of disk drives, it is desirable to reduce the distance between the head and disk (flying height) or accelerate the rotation of the disk. However, in either situation, the head may come into contact with the disk more often and, thereby, transfer lubricant from the surface of the disk to the head. Because lubricant transfer results in lubricant build up on the head, which can result in high fly write (HFW) problems, Solvay-Solexis and others have made available products such as “Fomblin Z-Tetraol,” which have lower mobility than Z-Dol. Nevertheless, due to compatibility issue with A20H, such lubricant systems may have significant limitations in composition and thus performance.